Study on adaptive‐passive eddy current pendulum tuned mass damper for wind‐induced vibration control

Tuned mass dampers (TMDs) are used to control wind‐excited responses of high‐rise building as traditional vibration control devices. A TMD will have an excellent control effect when it is well tuned. However, a traditional passive TMD is sensitive to the frequency deviation; the mistuning in frequency and damping ratio both will decrease its control effect. In the previous research, an adaptive‐passive variable pendulum TMD (APVP‐TMD) is proposed, which can identify the TMD optimal frequency and retune itself through varying its pendulum length. However, it is found that the frequency variation will change the TMD damping ratio, and an unreasonable damping ratio will lead to a decrement in the robustness of a TMD. In this study, an adaptive‐passive eddy current pendulum TMD (APEC‐PTMD) is presented, which can retune the frequency through varying the pendulum length, and retune the damping ratio through adjusting the air gap between permanent magnets and conductive plates. An adjustable eddy current pendulum TMD (PTMD) is tested, and then, a single‐degree‐of‐freedom (SDOF) primary model with an APEC‐PTMD is built, and functions of frequency and damping ratio retuning are verified. The 76‐story wind‐sensitive benchmark model is proposed in the case study. The original model without uncertainty and ±15% stiffness uncertainty models are considered, and response control effects of different controllers are compared. Results show that because the APEC‐PTMD can both retune its frequency and damping ratio; it is more robust and effective than a passive TMD. It is also found that the APEC‐PTMD has a similar control effect with the active TMD, with little power consumption and better stability.     

结构被动和主动多重调谐质量阻尼器控制策略的发展

广泛评述了被动多重调谐质量阻尼器(MTMD)的研究现状，提出了结构主动多重调谐质量阻尼器(AMTMD)和多重主被动调谐质量阻尼器(MAPTMD)的新控制策略，介绍了从AMTMD和MAPTMD的研究进展，并指出了进一步研究的发展方向。     

Effects of tuned mass damper on correlation of wind‐induced responses and combination coefficients of equivalent static wind loads of high‐rise buildings

Tuned mass dampers (TMDs) are employed to control the wind‐induced responses of tall buildings. In the meantime, TMD may have an impact on the correlation of wind‐induced responses and combination coefficients of equivalent static wind loads (ESWLs). First, the mass matrix and stiffness matrix were extracted in this paper in accordance with the structural analysis model of two high‐rise buildings, and on that basis, the wind‐induced vibration responses analysis model with and without TMD was established. Second, the synchronous multipoint wind tunnel test to measure the pressure was performed for two high‐rise buildings, and the time history of wind‐induced vibration responses with and without TMD was studied. Finally, the impact of TMD on the correlation of wind‐induced responses and combination coefficients of ESWLs was discussed. The results of two examples suggest that after the installation of TMD, the increase of ρ_xy was 2.1% to 35.0% and ρ_yz was 2.8% to 45.6% at all wind directions for Building 1, and the increase of ρ_xy was 3.9% to 17.1% and ρ_yz was 6.8% to 38.3% for Building 2. The combination coefficients of ESWLs of two buildings were 3% to 6% larger than that of the original structure. The conclusion of this paper can be referenced by the wind resistant design of high‐rise buildings with TMD.     

Coupled shear‐flexural model for dynamic analysis of fixed‐base tall buildings with tuned mass dampers

An equivalent discrete model is developed for time domain dynamic analysis of uniform high‐rise shear wall‐frame buildings with fixed base and carrying any number of tuned mass dampers (TMDs). The equivalent model consists of a flexural cantilever beam and a shear cantilever beam connected in parallel by a finite number of axially rigid members that allow the consideration of intermediate modes of lateral deformation. The proposed model was validated by a building whose lateral resisting system consists of a combination of shear walls and braced frames. The results showed the effectiveness of TMDs to reduce the peak displacements, interstory drift ratio, and accelerations when the building is subjected to a seismic load. The root mean square accelerations due to along‐wind loads also decrease if TMDs are attached to the building.     

Experimental parametric study on wind‐induced vibration control of particle tuned mass damper on a benchmark high‐rise building

A particle tuned mass damper system is an integration of tuned mass damper and particle damper. The damping performance of such device is investigated by an aero‐elastic wind tunnel test on a benchmark high‐rise building. The robustness of the system is studied by comparing the damping performance to that of a traditional tuned mass damper, and the results show that the damper has excellent and steady wind‐induced vibration control effects. Meanwhile, the parameters (filling ratio, mass ratio, and mass ratio of the container to particles), which have great influence on the vibration reduction performance of the system, are also analyzed, and it is found that the particles filling ratio plays the most important role in deciding the damping effects of the dampers. There exists an optimum filling ratio and mass ratios in which the damper can reach the best damping state. Proper parameter selections can greatly improve the damping performance.     

地震作用下某高层结构MTMD减震控制研究

通过数值模拟研究了地震作用下高层结构多个调谐质量阻尼器(MTMD)减震控制。根据实际工程,利用国际通用软件ETABS建立了结构三维有限元模型,进行了动力特性的分析,得到了结构的前几阶频率;根据不同场地类型,选取了4条典型的地震波;研究了调谐质量阻尼器(TMD)的参数选取和有限元的模拟;运用时程分析方法,分别研究了不同地震作用下高层结构有无控制下的反应。研究结果表明,MTMD对高层结构的减震控制效果明显,场地类型对减震控制效果有一定的影响。所获得的结果为高层结构减震控制设计提供参考和依据。     

Coupled‐two‐beam discrete model for dynamic analysis of tall buildings with tuned mass dampers including soil–structure interaction

An equivalent coupled‐two‐beam discrete model is developed for time‐domain dynamic analysis of high‐rise buildings with flexible base and carrying any number of tuned mass dampers (TMDs). The equivalent model consists of a flexural cantilever beam and a shear cantilever beam connected in parallel by a finite number of axially rigid members that allows the consideration of intermediate modes of lateral deformation. The equivalent model is applied to a shear wall–frame building located in the Valley of Mexico, where the effects of soil–structure interaction (SSI) are important. The effects of SSI and TMDs on the dynamic properties of the shear wall–frame building are shown considering four types of soil (hard rock, dense soil, stiff soil, and soft soil) and two passive damping systems: a single TMD on its top (1‐TMD) and five uniformly distributed TMDs (5‐TMD). The results showed a great effectiveness of the TMDs to reduce the lateral seismic response and along‐wind response of the shear wall–frame building for all types of soils. Generally speaking, the dynamic response increases as the flexibility of the foundation increases.     

Improving the wind‐induced human comfort of the Beijing Olympic Tower by a double‐stage pendulum tuned mass damper

With five sub towers and a maximum height of 246.8 m, the Beijing Olympic Tower (BOT) is a landmark of Beijing. The complex structural properties and slenderness of the BOT render it prone to wind loading. As far as the wind‐induced performance of this structure is concerned, this paper thus aims at a tuned mass damper‐based mitigation system for controlling the wind‐induced acceleration response of the BOT. To this end, the three‐dimensional wind loading of various wind directions are simulated based on the fluctuating wind force obtained by the wind tunnel test, by which the wind‐induced vibration is evaluated in the time domain by using the finite element model. A double‐stage pendulum tuned mass damper (DPTMD), which is capable of controlling the long period dynamic response and requires only a limited space of installation, is optimally designed at the upper part of the tower. Finally, the wind‐induced response of the structure with and without DPTMD is compared with respect to various wind directions and in both the time and frequency domains. The comparative results show that the wind‐induced accelerations atop the tower with the wind directions of 45, 135, 225, and 315° are larger than those with the other directions. The DPTMD significantly reduces the wind‐induced response by the maximum acceleration reduction ratio of 30.05%. Moreover, it is revealed that the control effect varies noticeably for the five sub towers, depending on the connection rigidity between Tower1 and each sub tower.     

Mitigation of tower and out-of-plane blade vibrations of offshore monopile wind turbines by using multiple tuned mass dampers

Offshore wind turbines are vulnerable to external vibration sources such as wind and wave excitations due to the increasing size and flexibility. It is necessary to mitigate the excessive vibrations of offshore wind turbines to ensure the safety and serviceability during their operations. Some research works have been carried out to control the excessive vibrations of the tower and the in-plane vibrations of blades. Very limited study focuses on the out-of-plane vibration mitigation of blades. In the present study, a detailed finite element (FE) model of the latest NREL 5MW wind turbine is developed by using the FE code ABAQUS. The tower and blades are explicitly modelled, and the rotating of the blades is considered. Multiple tuned mass dampers (MTMDs) are proposed to be installed in the tower and each blade to simultaneously mitigate the out-of-plane vibrations of the tower and blades when the wind turbine is subjected to the combined wind and wave loadings. The effectiveness and robustness of the proposed method are systematically investigated. Numerical results show that MTMDs can effectively mitigate the out-of-plane vibrations of the tower and blades when the wind turbine is in either the operational or parked condition.     

A combined tuned damper and an optimal design method for wind‐induced vibration control for super tall buildings

The wind‐induced vibrations of super tall buildings become excessive due to strong wind loads, super building height and high flexibility. Tuned mass dampers (TMDs) and tuned liquid column dampers (TLCDs) have been widely used to control vibrations for actual super tall buildings for decades. To fully use both the economic advantage of the TLCD system and the high efficiency of the TMD system, an innovative supplemental damping system including both TLCD and TMD and called combined tuned damper (CTD), which can substantially decrease the cost of the damper, was proposed to control the wind‐induced vibrations of tall buildings. The governing equations are generated for the motion of both the primary structure and the CTD and solved to anticipate the dynamic response of the CTD‐structure system. Moreover, an optimal design method of human comfort performance is proposed, in which the life cycle cost of the damper‐structure system is considered as the quantitative index of the performance. The life cycle cost includes the initial cost, the maintenance cost and the failure cost. The failure cost can be calculated using the vibration‐sensation rate model, which is based on the Japanese code AIJES‐V001‐2004. Copyright © 2016 John Wiley & Sons, Ltd.     

Shaking table model test and FE analysis of a reinforced concrete mega‐frame structure with tuned mass dampers

To study the damage characteristics and to evaluate the overall seismic performance of reinforced concrete mega‐frame structures, a shaking table test of a 1/25 scaled model with a rooftop tuned mass damper (TMD) is performed. The maximum deformation and acceleration responses are measured. The dynamic behavior and the damping effect with and without TMD are compared. The results indicate that the mega‐frame structure has excellent seismic performance and the TMD device has a significant vibration reduction effect. A finite element (FE) model simulating the scaled model is also developed, and the numerical and experimental results are compared to provide a better understanding of the overall structural behavior in particular those related to the dynamic characteristics and damping effect. Upon verification of the FE model, other important structural behavior can also be predicted by the FE analysis. Copyright © 2014 John Wiley & Sons, Ltd.     

Wind tunnel study of the across-wind response of a slender tower with a nonlinear tuned mass damper

The effectiveness of a class of nonlinear tuned mass dampers (TMDs) in suppressing across-wind structure oscillations was examined through a wind tunnel test. The nonlinear TMD employed a wire rope spring to replace both the spring and the damper required in a typical system. First, a single degree of freedom aeroelastic stick model of a slender structure with a square cross-section was tested under different levels of damping. The measurements obtained from the tests were used to determine the root-mean-square (RMS) of the lift coefficient and other aerodynamic parameters. In the second phase of testing, the nonlinear TMD system was attached near the tip of the aeroelastic model. The response reduction achieved by adding the TMD was considerable and was quantitatively expressed in terms of an equivalent viscous damping. A comparison between the nonlinear TMD and an equivalent optimized linear TMD was made. Probability-based procedures were developed to estimate the equivalent damping provided by the nonlinear TMD. The estimated damping was compared with that obtained experimentally to evaluate the accuracy of the prediction method.     

Mechanism and optimum design of shared tuned mass damper for twin‐tower structures connected at the top by an isolated corridor

The concept of shared tuned mass damper (STMD) for twin towers linked by a sky corridor using flexible joints is proposed in this paper. The analytical expressions of the transform functions and random earthquake responses of the flexibly connected structures are derived using a three‐degrees‐of‐freedom model system. The seismic reduction mechanism of the STMD is revealed using comparative analysis between the structures with STMD and those connected using a viscoelastic damper. The effect of the nondimensional parameters such as the frequency ratio of the two primary structures, mass ratio, tuning frequency ratio of the corridor, and damping ratio of the passive control devices on the structural seismic response is investigated. Optimum parametric analysis is performed using the principle of minimizing the displacements of both towers, and the optimal parameter formulas are established. Numerical analysis is conducted to verify the control effectiveness of the connected multi‐degree‐of‐freedom system subjected to the El Centro earthquake ground motion. The results show that the earthquake responses of the towers can be effectively reduced if the parameters of the flexible connecting elements are appropriately selected for a certain corridor mass. Moreover, a remarkable seismic reduction effect can be achieved if the towers have similar dynamic properties.     

Performance‐based wind evaluation and strengthening of existing tall concrete buildings in the Los Angeles region: dampers,nonlinear time history analysis and structural reliability

This paper presents a methodology in wind design including in a scientific way the benefits of using dampers and of performing a nonlinear dynamic analysis of tall concrete buildings that are being evaluated and strengthened. It is developed for tall buildings in the Los Angeles region but is without geographic bounds. The uses of equations of structural reliability form this scientific basis. Copyright © 2013 John Wiley & Sons, Ltd.     

Shaking table test and numerical simulation on vibration control effects of TMD with different mass ratios on a super high‐rise structure

In this paper, the influence of mass ratio on the vibration control effects of tuned mass damper (TMD) on a super high‐rise building has been investigated. A 1/45 scaled model of a super high‐rise building was constructed, and the TMD with the mass ratio of 0.01, 0.02, and 0.03, respectively, was suspended on the top. Shaking table test and the corresponding numerical simulation were carried out to make a further understanding of the damping mechanism. The structural performance with or without TMD was comparatively studied. The results show that larger mass ratio can improve the control effects under frequent earthquake, but the control effects increase little with the increase of mass ratio under rare earthquake due to structural damages, accompanied by stiffness degradation and nonlinear behavior of the main structure. In addition, some suggestions on the mass ratio selection are also proposed to generalize its applications.     

Experimental study on the seismic behavior of a shear wall with concrete‐filled steel tubular frames and a corrugated steel plate

Shear walls and core tubes in shear walls constitute the core anti‐earthquake vertical systems of high‐rise buildings. This paper proposes a new type of composite shear wall with concrete‐filled steel tubular frames and corrugated steel plates. The seismic behavior of the new shear wall is studied using a cyclic loading test and damage analysis. The failure mode, load‐carrying capacity, ductility, stiffness degradation, hysteresis behavior, and energy dissipating capacity exhibited in the test are studied. The test results show that when the proposed wall is broken, the tension side of concrete‐filled steel tubes is torn. The concrete at the bottom of the wall is detached and peels off along the through cracks. The energy dissipation capacity of concrete walls is more fully utilized. The proposed wall exhibits excellent deformability, energy dissipation capacity, and the stiffness degradation was slower than that of other walls. The use of corrugated steel plate significantly improved the seismic performance while simultaneously increasing the ductility and reducing the damage. In addition, this paper modified the energy dissipation factor in the Park & Ang model based on the situation of the specimen and experiment. It can be used to evaluate the damage degree of this new type of shear wall.